Plyometrics

An exciting development for Middle Distance running is that research performed in Sydney at the University of Technology by Robert Spurrs and other researchers. It has revealed that Plyometric Training can have a strong positive effect on performance in endurance running events. Seventeen male distance runners with a training history of average 10 years were randomly assigned into an experimental (Plyometric training) group (E) and a control group (C). The experimental group then completed a 6 week plyometric program (first 3 weeks 2 sessions/week, second 3 weeks 3 sessions/week).  Both groups continued training normally (60-80km/week). The Plyometric program progressed from 60 total contacts each session in the first week to 180 each session in the final week. The intensity also progressed from exercises such as squat jumps, double leg bounds in week 1 to alternate leg bounds, single leg hops, depth jumps, double leg hops and single leg hurdle hops in the final 2 weeks.

Both groups were tested prior to and after the 6-week training period for all variables. The testing resulted in the following:

Group E improved 13.2% in the Counter Movement Jump, Group C no significant change.
Group E improved 7.8% in the 5 bound test, Group C no significant change.
Group E improved Running Efficiency at 6.7%  at 12kph, 6.4% at 14kph, 4.1% at 16kph , Group C no significant change at any velocity.

Group E improved Musculotendinous stiffness at heavy loads by 11-15%, Group C no significant change.
Group E improved Maximal Isometric Force by 11-13% , Group C no significant change.
Group E improved Rate Force Development by 14-15%, Group C no significant change.
Group E improved 3km Time Trial by 2.7% which was in reality an average of 16.6s, Group C had no significant change.
Group E & C both showed no significant change in VO2max , Lactate accumulation or Lactic Threshold

 

The improvement in 3km running performance occurred without any change in VO2max and Lactate Threshold while body mass showed no change in pre and post testing. It was concluded that improvement in Running Efficiency had lead to the the significant drop in 3km time. It was also suggested that the increased Musculotendinous stiffness and the resulting increase in maximal force production of the lower limb had transferred into improved Running Efficiency. Similar has been reported by other researchers eg Paavolainen et al.

 

Many International athletes have used Plyometrics as an important part of their program. It has been reported that Hicham El Guerrouj does 300 impacts using a variety of jumps on a weekly or fortnightly basis in the off-season.Svetlana Masterkova regularly performed 10 reps of bounding over 100m. I have also observed Wilson Kipketer doing a session of relaxed quick contact bounding over 80m while training in Sydney.

A great article on the preparation of Steeplechase athletes described a way of integrating weight training and plyometrics. It was interesting that the authors highly recommended that the athletes complete a moderate pace 6-8km run after all speed strength training sessions.This was most likely an attempt to transfer neural gains from speed-strength training into the endurance running action.

 

I have seen athletes in my squad improve their finishing kick and mid-race acceleration by a large amount after we have seen gains in Plyometric ability. This has also been reported by others eg. de Swardt.

 

From a physiological basis, if a muscle is pre-stretched or made to build up high tension, it will concentrically contract with a much greater force. Plyometrics make use of this factor. The key in performing plyometrics is that the response from the ground must be immediate. Otherwise the exercise turns into a concentric contraction and does not involve the stretch reflex.

 

Any kind of Speed-strength training can have a temporary negative effect on an athlete’s nervous system and therefore their current level of speed-strength performance. Vern Gambetta has commented that any activity of high nervous system demand (like Plyometrics) will take twice the recovery time as compared to a similar load of metabolic work. However, rapid improvement occurs after the load volume has been reduced and changed to a maintenance regimen. Positive changes of a greater magnitude occur after a certain amount of time has passed following the reduced training load. It is very important to plan the situation so that the highest level of speed-strength capacity occurs during the peak competition period. Some international athletes that use Plyometrics for a big part of the training year stop doing it at least 4 weeks before the main competition period.

 

The physiological theory behind plyometric training is to develop efficiency in the stretch/shortening cycle of muscle action. During the stretch (eccentric lengthening phase) of muscle action, a greater amount of elastic energy is stored in the muscle. This elastic energy is then re-used in the shortening (concentric) muscle action that follows, to make it stronger. The key is to shorten the switching time i.e.  the time it takes for the muscle to change from the eccentric lengthening phase to the shortening work phase. The fundamental principle of plyometric training is that it is the rate, not the magnitude, of the stretch that determines the utilization of elastic energy and the transfer of chemical energy into mechanical work.

 

 

Regards

Steve Bennett

www.oztrack.com

 

A good book to do with Plyometrics is
Jumping into Plyometrics
by Donald Chu